The invention relates to methods and apparatus for inserting a catheter into a body cavity and, more particularly, though not exclusively, to methods and apparatus for inserting a multi-lumen split-tip hemodialysis catheter into a blood vessel for hemodialysis.
Multi-lumen catheters are desirable for various treatment applications such as hemodialysis where fluid extraction and infusion occur simultaneously. These multi-lumen catheters provide a single catheter application having multiple lumen channels each supporting independent flow, thus precluding the need for inserting multiple catheters or multiple-catheter assemblies. Further, because a patient might require frequent dialysis, often only days apart, it is desirable to secure placement of the catheter for extended periods of time. Extended placement, however, requires extreme catheter flexibility to avoid damage to the vessel and permit the catheter to move in the blood flow to minimize the possibility of the catheter remaining in pressure contact with the wall of the vessel for prolonged periods.
Unfortunately, the desired flexibility of these catheters presents insertion difficulties. For example, simply advancing the catheter over a guidewire is very difficult since the catheter lacks sufficient stiffness to slide easily through the vessel wall and into the blood vessel to the desired location. Flexible catheters present additional difficulties associated with subcutaneous tunneling and placement.
Known insertion methods and assemblies attempt to overcome, or at least mitigate, these insertion difficulties by stiffening the catheter temporarily during the insertion process. For example, one known method involves temporarily inserting a rigid tubular applicator into one of the lumens. This permits the stiffened catheter/applicator assembly to be passed over a guidewire into a desired position, at which point the applicator can be removed. For example, U.S. Pat. No. 5,405,341 attempts to solve the problem with a single rigid applicator that is designed for insertion into one lumen but also passes through a portion of the second lumen (at the distal end of the instrument) to effectively stiffen the two lumens of the catheter together during insertion. This approach is cumbersome, at best, and presents additional difficulties in maneuvering the instrument. Further, this temporary rigid applicator approach, however, is poorly suited for placement of a catheter having a split at its distal end into two or more separate lumens (e.g., to further isolate a fluid extraction lumen from a return infusion lumen) because only one tip can be secured.
Hence, there exists a need for better and more effective methods and apparatus for insertion of flexible catheters into vessels.